1. Field of the Invention
The present invention relates generally to fiber optic cable assemblies deployed in fiber to the premises applications, and more specifically, to fiber optic ribbon cable assemblies including at least one network access point and methods for handling the ribbon stack at the network access point to address translation and rotational issues.
2. Technical Background
Fiber optic networks are being expanded to provide voice, video, data and other services to subscribers. As a result, different cable types are being used to span both the long and short transmission distances. For kilometer length distribution cables, for example, these cables typically include one or more network access points along the cable length at which pre-selected optical fibers are accessed and preterminated to provide a branch off of the distribution cable. These network access points or “NAPs” are also referred to as “mid-span access locations” or “tap points.” Preterminated optical fibers are often spliced or otherwise optically connected to tether or drop cables. The types of networks in which cable assemblies are being developed are often referred to as “FTTx” networks, where “FTT” stands for “Fiber-to-the” and “x” generically describes an end location.
While network access points have been created along cables including non-ribbonized optical fibers, ribbon cables present unique challenges for accessing. Specifically, challenges in how the access is performed, how the fibers are terminated, how the remaining uncut optical fibers or ribbons are handled, and how the cable performs over time and under stress. There are also challenges in mid-span accessing ribbon stack containing cables of various designs. Thus, there is a need in the art for treating a network access point of specific types of ribbon cables.
One type of ribbon cable currently available is the Standard Single-Tube Ribbon (SST-Ribbon™) cable available from Corning Cable Systems of Hickory, N.C. This particular cable is helically wound and contains readily identifiable 12-fiber or 24-fiber ribbons in a filled buffer tube. Dielectric or steel rods are placed about 180 degrees apart in the cable's jacket to provide the required tensile strength for armored and dielectric constructions, respectively. This cable exhibits excellent water-blocking performance and is jacketed with a polyethylene outer jacket and armored cables include a copolymer-coated steel tape armoring.
Another type of ribbon cable currently available includes the SST-Ribbon™ Gel-Free Cable also available from Corning Cable Systems of Hickory, N.C. The cable includes a single buffer tube that contains a stack of up to eighteen 12-fiber ribbons wrapped within a water-swellable foam tape. This central buffer tube is surrounded by a second water-swellable tape. Dielectric or steel strength members are located 180 degrees apart under the cable jacket to provide tensile and anti-buckling strength. The cable sheath is jacketed with a black UV-resistant polyethylene sheath and armored cables include a copolymer-coated corrugated steel tape armor layer. This cable can provide, for example, about 216 fibers in a compact design that can fit within a 1.0 inch inner diameter or larger inner-duct. Coupling features ensure that the ribbon stack and cable act as one unit, providing long-term reliability in aerial, duct and direct-buried applications and minimizing ribbon movement in situations where cable vibration may occur.
What is desired is a cable assembly having at least one network access point and wherein the distribution cable is of a type including a stack of optical fiber ribbons, such as the cable types described above. A desirable ribbon cable assembly would provide structure or material for handling both the uncut ribbon stack portion as well as the preterminated ribbons. Further, what is desired are methods of creating network access points along a ribbon stack containing cable that handles ribbon stack rotational and translational issues between the core and the cable sheath.